DAS alcohol solubility?
The free acid salt of DAS (sodium free) seems only to be soluble in some alcohols such as ethanol but not water, so I guess it is possible that DAS may also be soluble in alcohol. If so, one could make an alcoholic solution and if soluble enough, store it in the fridge. Of course this may be unnecessary if the shelf-life reported by Kees is repeatable.
If a rich alcoholic solution is possible, then adding drops of this (with quick stirring) to a much larger emulsion volume may be a convenient way to incorporate higher amounts.